This invention relates to an electronic ignition device for combustion engines having an ignition coil coupled to the combustion engine by way of a magnet wheel, wherein the primary circuit of the coil is interrupted at the desired ignition instant by a transistor switch, and wherein the switching transistor is then switched on by means of an electronic component between its base and collector, and is finally turned off at the ignition instant by a control element.
Many such electronic ignition devices have been known. As examples only, we refer to the German DOS No. 2,730,002 and DOS No. 2,686,428. All of these conventional known ignition devices have the common feature that when the primary coil is excited, the transistor switch is switched on by way of an electric component in the form of a resistance. The control transistor (which may, or course, alternatively be a control thyristor) shortcircuits the base and the emitter of the transistor switch at the ignition instant, so that it interrupts the energy flow in the primary coil, thereby producing the ignition voltage by induction in the secondary coil.
In all known switching systems, a voltage divider determines when the switch transistor is to be cut off by the control element. This has the disadvantage, however, that such a voltage divider must be aligned and that it is necessary to provide temperature compensation for the transistor switch as well as for the control element.